I think that sounds like a perfect way to cook mustard greens. I'm not a big fan of them, but I'll eat them when cooked along with chopped bacon and some onion. I need that smoky saltiness from the bacon to help with the bitterness of the greens. I think salt pork has enough salt for both the greens and the potatoes.

Mustard greens have a peppery, kind of strong flavor. When I cook them, I sautee a chopped onion, several minced garlic cloves, red pepper flakes in olive oil, and sometimes add a few tinned anchovies instead of salt, plus freshly ground black pepper. The greens are washed in "several waters", drained, and added to the sautee pot ( I tend to use a large sauce pot instead of a sautee pan) and wilted till tender with the cover on....gently stirring every now and then. I like them better when they are tender but still retain their green color.

They can be eaten as a side dish, but I have also combined them with a cut macaroni like penne or ziti....drizzled with a little more olive oil and dusted with grated Romano cheese. I like bitter greens so we have these or broccoli rabe fairly often. In my mind they're similar... but uniquely different.

they were dried, so after the potatos sauteed for a bit with the onions and garlic in the pork fat I added hte mushroomliqoud and let the potatos cook in that. After the potatos were done I added the mushrooms themselves fresh thyme, rosemary, chervil, and parsley and the greens. I dumped a little parm and some lemon juice in at the very end.

We add steamed potates occasionally, either the tiny red bliss or fingerlings... now I'll have to try your addition of porcini. That's sounds delicious. Funny, but I never did like an acidic addition to any greens I've cooked.